cabela's sells a bipod for an SKS that just slips over the barrel, and i have seen them made for shotguns also. you could also check the turkey hunting sections, or simply mount a swivel stud and attach a bipod to it just as you would on a rifle.
yes it does. why its so hard to find something. thought about getting a tube extension. then i would be able to make something work. kind of exspensive though. figure someone would make a clip on one for a shotgun.
Have you looked at the Stoney Point shooting sticks? I really like mine. They have several options to choose from including one that snaps on to the shotgun barrel. www.stoneypoint.com
the nova is already heavy how much weight do you want to lug around the field?
I suggest making a set of shooting sticks cost you about 5 bucks. They will work great for all your guns they are light weight and if you need to swing the gun you can just drop the sticks or leave them in the truck. They also make a handy walking stick.